1. Field of the Invention
The present invention relates to an illuminating apparatus, and more particularly to an illuminating apparatus and control method for keeping a constant total brightness of ambient light and light produced by the illuminating apparatus.
2. Description of Related Art
Intelligent household appliances are developed for providing people with a convenient living environment. Sensor-activated LED illuminating apparatus is one of the popular intelligent household appliances.
A conventional sensor-activated LED illuminating apparatus comprises a lamp and an optical sensing switch for detecting ambient brightness. The optical sensing switch is electrically connected to the lamp. When the ambient brightness is lower than a threshold brightness, the optical sensing switch is turned on to activate the lamp. When the ambient brightness is higher than the threshold brightness, the optical sensing switch is turned off to inactivate the lamp. Hence, the lamp can be automatically activated under poor illumination and is inactivated under sufficient illumination.
The natural ambient brightness in environment changes gradually. For example, the ambient brightness gradually changes through dawn, morning, sunset and night or through sunny day and cloudy or rainy day. However, the LED illuminating apparatus operates only in two statuses: turned-on and turned-off without adjustable degrees of brightness.
Based on a user's habit for using the LED illuminating apparatus, the light produced from the LED illuminating apparatus should be bright enough in complete darkness. But the LED illuminating apparatus may be turned on in cloudy or rainy day or at dawn with some dim light in the ambient environment. In that case, the LED illuminating apparatus over illuminates with excessive brightness, causing waste of electric power energy. The conventional LED illuminating apparatus is still inadequate as an intelligent household appliance for saving electric power energy.